Electric temperature control



Nov. 29, 1927. 1,651,236

c. B. THWING ELECTRI C TEMPERATURE CONTROL Filed Aug. 27. 1925 2 Sheets-Sheet l 4 Q E m fiwenfzv 6750714157 j fiiiw Nov. 29, 1927. 1,651,236

c. B. THWING ELECTRIC TEMPERATURE CONTROL Filed Aug. 2'7. 1925 2 Sheets-Sheet 2 ZZ ZA iga/ Patented Nov. 29, 19 27.

UNITED STATES PATENT OFFICE.

CHARLES B. THWING, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THWING IN STBUMENT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRIC TEMPERATURE CONTROL.

A pplioation filed August 27, 1925. 'serial No. 52,948.

My invention relates to control systems,

- and it has particular relation to an electrical temperature control system.

One object of my invention is to provide a 6 simple, reliable and accurate system of apparatus for use in controlling, either manually or automatically, the temperature of metal rolls, such as are used in calendering, ironing, rubber working and other machines including rolls which are heated or cooled under operating conditions.

Another object of my invention is to provide novel means for indicating the temperature at the surface of a roll under conditions of use, and the invention further contemplates a relatively simple device whereby the supply of a heating medium such as water, steam or electric current shall be automaticallyregulated in accordance with temperature changes at the working surface of the roll.

A further object of my invention is to provide a novel galvanometer control switch particularly designed to govern one or more electric circuits when the needle or other moving element of the galvanometer occupies a predetermined and definite position.

A still further object of my invention is to provide quick and accurate means for conveniently adjusting the deflection at which the galvanometer causes the operation of the switch.

*A-still further object of my invention is to provide means for varyin the sensitivity of the galvanometer, where y the current flow necessary to actuate the galvanometer needle to a selected position may be controlled without changing the zero setting of the instrument, or the position of the switch,

thus effecting the adjustment of the selected position from a point outside the instrument, thereby avoiding the possibility of damage to the sensitive mechanism of the instrument.

With-these and other objects and applications in mind, my invention further consists in the details of construction and operation and circuit arrangement, hereinafter described, and claimed and illustrated in the accompanyin drawings, :wherein I Fig. 1 is a 'agrammatic view, partlally in section, of circuits and apparatus embodying my invention;

Fig. 2 is an enlarged detail view, illustrating the electric connections between the motor-actuated switch, the galvanometer and the water heater; and

Fig. 3 is a detail view of a modification.

In the illustrated embodiment of my invention shown in the drawing, a hollow roll 1 is mounted in bearings 2 and 3 and it is driven from a suitable source of power (not shown) through a gear or pulley 4. In the case illustrated, the roll is desi' ned to be heated by water supplied throug a pipe 5 from an electric water heater 6 and extending into one end of the roll through a suitable stuffing box or equivalent device (not shown). The water flows out of the roll through a waste pipe 7.

In accordance with my invention, at a suitable point in the cylindrical or working surface of the roll preferably adjacent its central plane, 1 form an inwardly taperin hole in which I mount a steel or other suitab e metallic plug 8. This is centrally perforated for the reception of a conductor 9 one end of which is welded at 8 to said plug at the outer surface thereof so as to be flush with the cylindrical surface of the roll in which it is mounted, The roll itself is of steel or cast iron and constitutes one of the elements of a thermocouple, while the conductor 9, which is made of constantan or some other nickel alloy, constitutes the second element of the couple.

Within the plug 8, the conductor 9 is suitably insulated to within a short distance of its welded extremity by a porcelain or other refractory tube 10 and from this tube within the roll 1 it is provided with a suitable flexible insulating coverin 11, being extended through one neck of the roll to a suitable terminal 12 on the outside of one end of the latter. Adjacent this endof the roll, I mount on it an insulating structure 13 carrying a metallic contact ring 14 and on the bearing 3, I mount an arm 15 carrying a brush 16 electrically engaging said. latter ring. From this brush and from the bearing 3 or other suitable portion of the frame in which the roll 1 is mounted, I run a pair of compensating leads 17 and 18 to a box or" container 19 kept by any suitable means at a constant temperature. For example, said device 26.

box may be supplied through a pipe 26 with steam at atmospheric pressure so thatthe terminals of the wires or leads 17 and 18 within it are likewise maintained atall times at the same temperature.

From the terminals of said leads within the box 19 I run two conductors. 21 and 22 to a suitable indicating galvanometer 23- and may also extend branch conductors 24 and 25 to a recording galvanometer or equivalent These instruments 23 and 26 are properly calibrated in degrees so that they respectively indicate and record the temperature at the hot junction of the thermocouple comprised by the roll 1 and conductor 9.

Moreover it is noted that temperatures shown are those of the external or working surface of said roll 1, so that by the means described it is possible to obtain accurate readings or indications of that portion of the roll engaging whatever material is operated on.

If it is desired to automatically regulate the supply of heating medium to the roll, I

may provide such an arrangement of apparatus as that shown in the drawings and more especially as illustrated in Fig. 2. For the purpose noted, the coil or heating element 30 of the electric heater 6 is connected to a suitable form of motor-actuated switch 31 which includes an oscillatory or pivotally mounted blade 32 capable of simultaneously engaging either of two pairs of fixed contacts 33-34 or 35-36. This blade is designed to be actuated by an electric motor 37 through suitable quick break mechanism which after said motor has been started, causes the blade to instantaneously move from engagement with one pair of contacts into engagement with the other pair whereon it'remains until the motor is again 0 erated. The contacts 36 and; 33 of the switch are both connected to a current supply line 38 and a second current supply main 45 is connected to one terminal of the heating element 30 as well as to a terminal 39 connected to one of the terminals of the motor 37. The second terminal of said motor is connected to a terminal 40.

In addition to the motor-controlled switch 31, I provide a controlling galvanometer 41 for governing a pair of switches having three terminals-42, 43,-and 44 of which the first is connected to the terminal 35 of the switch 31. The terminal 43 is connected to the terminal 40 and the terminal 44 is connected to the motor terminal 34. The second current sup ply lead 45 is connected to the motor termi nal 39 and to one terminal of the heating coil 30.

The galvanometer 41 may be of any suitable construction capable of bein actuated by the current produced by the t ermocouple cdmprised by the elements 1 and 9 and includes a movable element in the form of mamas The winding 41 of the galvanometer is connected in circuit with two terminals 47 and 48 to which are connected the leads 21 and 22 and in one of these leads I preferably connect a control rheostat 49 whereby the current flow from the thermocouple may be adjusted to produce any desired deflection of the needle 46.

The rheostat of the control rheostat 49 is one of the important features of my invention, inasmuch as the range of the alvanometer may be quickly and easily ad usted without the necessity for shifting the switches to the zero position of the galvanometer needie, as required by the prior art. In accordance with the present construction, said contacts and said zero position remain unchanged, and it is only necessary to vary the control rheostat 49 when the selected position for the galvanometer needle is to be varied. A further advantage of the present method is that the sensitivity of the galvanometer 41 is increased as the desired maximum temperature reading is decreased, whereas in the prior art constructions, the sensitivity remains unchanged as the zero position of the instrument is depressed or the contacts adjusted.

Mounted to cooperate with the needle 46 is a depressor 50 in the shape of a substantially horizontal element mounted over said needle adjacent the free end thereof and having at its extremity downwardly projecting stops 5151 which limit the possible swing of said needle. This depressor, by suitable mechathereby when it is depressed, I mount two levers 52 and 53 in the form of two ali ned bars so mounted as to extend in substantlally the same horizontal line, with their short arms immediately adjacent each other but spaced apart. At the end of the long arm of the lever 52 is mounted an insulated contact 54 and a similar contact 55 is mounted on the end of the long arm of the lever 53 while adjacent and immediately above these two contacts are mounted two fixed contacts 56 and 57, the arrangement being such that if, when the depressor 50 is lowered, the needle 46 lies over the short arm of one of the levers, that lever will be turned on its fulcrum and the contact on its long arm will be moved into electrical engagement with the corresponding fixed contact. The space between the ad acent ends of the levers 52 and 53 is of such width that if the needle 46 is immediately over it when the depressor is lowered, neither lever will be actuated, this position of the needle being that corresponding to the selected temperature at which it is desired the surface'of the roll shall be mainthe motor switch blade 32 in the position illustrated, and it cold water be supplied to the electric heater 6 and delivered therefrom through the pipe 5 to the roll 1, current will flow from the line 38 through the blade 32- 'to the heating coil and thence to the line 45 so that said water will be heated. The temperature of the surface of the roll is thus graduall raised and if the actuating mechanism 0 the depressor 50 be set in operation, said depressor will periodically move down and as long as the needle 46 of the galvanometer lies over the short arm of the lever 52, the contact 54 of this lever will be moved into engagement with the fixed contact 56 at each operation of said depressor. This, however, causes no opera tion of any of the apparatus since this particular pair of contacts is open circuited.

As the temperature of the roll 1 approaches the predetermined desired point, the galvanometer needle 46 moves toward the right, and when said temperature reaches said point, said needle, by proper adjustment of the rheostat 49 is caused to occupy a position immediately over the space a: between the adjacent ends of the levers 52 and 53. Should it be desirable at any time to vary the selected position for the galvanometer or needle 46, it is only necessary to adjust the control rheostat 49. When the depressor 50 acts, neither of the levers 52 or 53 is moved. Inasmuch, however, as current is still supplied to the coil 30, the temperature of the water in the heater 6 continues to rise, so that the roll temperature is also increased. The current produced by the thermocouple formed by the roll 1 and element 9 is consequently increased in amount, so that the galvanometer needle 46 swings further toward the right, with the result that subsequent action of the depressor 50 causes the lever 53 to be turned on its fulcrum, thus bringing its contact 55 into engagement with the contact 57. Ourrent is now free to flow from line 38 through the switch blade 32 to the contact terminal 44 thence through the contacts 57 and 55 to the contact terminal 43, to the contact 40 through notor 37 to contact terminal 39 and to the line 45. Said motor is thereupon put into operation and moves the switch blade 32 from the position shown in the drawings into engagement with the contacts and 36. This cuts ofi current from the coil 30 of the heater 6, so that there is no further rise in temperature of the water delivered to the roll 1 which is now cooled by said water. The switch blade 32 is, however, thus set so that while no action occurs as long. as the galvanometer needle 46 is moved by the depressor into engagement with the lever 53, or is moved into the space between the levers, as soon as the temperature of the roll has fallen to such a point that said needle swings over the short end of the lever 52, the next subsequent action of the depressor will cause the contact 54 to be moved into engagement with the contact 56. Thereupon current will flow from the line 38 through the blade 32, to contact terminal 42, thence through contacts 56 and 54 to contact terminal 43 thence to contact terminal through motor 37 to contact terminal 39 and to line starting motor 37 and causing it to move switch blade 32 into the position shown in the drawings in engagement with v the contacts 33 and 34. Current is now free to flow from the line 38 through the blade 32 to the heating coil 30 and the line 45, and while no further action of the motor 37 occurs by reason of the action of the depressor as long as the needle 46 lies over the lever 52 or over the space between the levers, an increase in the temperature of the roll with a corresponding increase of the thermoelectric current delivered .to the galvanometer 41 will cause the needle to'again move over the lever 53, whereupon the above described cycle of operations is repeated.

At any time the temperature of the working surface of the roll may be noted from the indicating galvanometer 23 and a record of the temperature variations of said working surface continuously made by the instrument 26.

The supply of heating medium to the roll is automatically governed by the apparatus described, so that the roll temperature is maintained between relatively narrow limits which may be accurately adjusted by the rheostat 49. If the amount of resistance in the galvanometer circuit is increased, a higher temperature of the roll will be reuired to generate suflicient current to deect the needle 46 into such a position that it may be depressed into engagement with the lever 53 which controls the cutting ofi of the current to the heater 6.

As shown in Fig. 3, I may in place of the electric heater 6 employ an electric magnet 60 to operate a valve 61 which in one position permits steam to flow from a pipe 62 to the roll 1 and in another position into which it moves under the action of gravity cuts ofi the supply of steam and permits cold water from a pipe 63 to be delivered to the roll. This electromagnet' 60 will be connected with the apparatus shown in Fig. 3 in place of the coil 30 so that when it is energized it will open the valve to allow steam to ow to the roll and when it is deenergized it will fall under the action of avity to cut ofi the steam and permit the i ow of cold water. If desired, the cold water connection to the above valve may .be omitted without cle parting from my invention where positive cooling of the roll is not required.

While I have shown several embodiments of my invention, for the purpose of describing the same and illustrating its principles of construction and operation, it is apparent that various changes and modifications may be made therein without departing from the spirit of my invention and I desire, therefore, that only such limitations shall be imposed thereon as are indicated in the appended claims or as are demanded by the prior art.

I claim 1. The combination with a roll adapted to constitute one element of a thermocouple, of

means controlled by said thermocouple for regulating the temperature of said roll, said means including means for varying the temperature at which said roll is to be maintained.

2. The combination of aheated metallic 'roll, an element electrically connected with the .roll to constitute therewith a thermocouple, and means controlled by the current from said thermocouple for regulating the temperature of the roll.

menace mechanism controlled by said instrument for governing the temperature of the roll.

5. The combinatwn of ametallic roll, an element electrically connected with said roll to constitute therewith a thermocouple, an

electrical instrument actuated by current from said thermocouple, and means governed by said instrument for maintaining the temperature of said roll substantially constant.

6. The combination of a metallic roll, an element electrically connected with said roll to form therewith a thermocouple, an electrical instrument actuated by current from said thermocouple, and means governed by said instrument for maintaining the temperature of said roll at apredetermined point, with means for adjusting said electrical instrument to vary the temperature at which said roll is maintained.

7. The combination with a metallic roll constituting one element of a thermocouple, an electrical instrument including a movable element actuated by current from said thermocouple, a periodically actuated depressor operative on the movable element, and an electric switch positioned to be actuated by the movable element when the latter occupies a predetermined position when dopressed.

8. The combination with a roll adapted to constitute one element of a thermocouple of an electrical instrument connected to said roll and including a movable element, a depressor periodically acting on said movable element, an electric switch positioned to be actuated by the movable element when the latter occupies a predetermined position when depressed, and means for adjusting the calibration of said electrical instrument.

In testimony whereof, I have hereunto subscribed my name this 24th day of August, 1925. I

CHARLES B. G. 

